It was the Plantagenet family's fortress in the 11th century. King Henri I Beauclerc (William the Conqueror's son) reinforced it one century later. A huge wall included the city bit by bit, a wall flanked by a dozen of big towers and a keep. Richard Lionheart, John Lackland and Henri II Plantagenet lived in Argentan's castle, their favourite one. Philip Augustus besieged the city in 1203, in order to annex it to kingdom of France.
Argentan was now a very important place: in 1374, the city was count of Alençon's privilege, later enlarged by lands from Anjou, Brittany, Normandy and even... Ile-de-France! Argentan became this huge territory's capital city.
Count Pierre II undertook the construction of a big seigniorial dwelling, in 1372: this was our ducal castle! This new building included the old fortress raised by the English. Those one were back during Hundred Years War: they besieged Argentan many time, burnt it in 1356, took the castle in 1417 and stayed there until 1449.
After this war came the war of Religion. King of France François I came in Argentan in 1517 and 1531 then the city was besieged by duke de Montgomery's troops in 1568. Fortunately, our palace resisted! The castle's garrison were hidden behind the church of St-Martin; they shot at the troop with cannons. The church was shaken, and the duke's troop burnt it, then ran as far as they could... Now, the last episode! King Louis XIII ordered the demolition of the keep in 1617...